
>>BROAD AND SHORT LIGHTING
EXAMPLE A

>> ISO 1250, 60mm, f/2.8, 1/160 sec.

>> ISO 1250, 60mm, f/2.8, 1/125 sec.
EXAMPLE B

>>>SHORT LIGHTING
In this photograph, a relatively small light source with an umbrella was used to light the particular side of the subject's face evenly. The reason why I haven't used the softbox is because I wanted a narrower beam of light than a softbox; also the light bounced by an umbrella helped to create a soft contrast between the highlights and the shadows. The left side of the subject's face--from her left cheek to her ear and hair on that side--are darkened, and thus her face looks thinner compared to the result of broad lighting.
In this case, the light source was placed like this:

>>>BROAD LIGHTING
In this photograph, a single light source with an umbrella was used because of the same reason with the first example. But this time the light source was positioned to the left side of the model at about a 45-degree angle, and at about height of the model's head. This lighting made the model's face looks broader compared to the short lighting since the highlights are mostly on the left side of her face.
In addition, this time the highlights on her eyes are not so white than that of the previous example with short lighting.
In this case, the light source was placed like this:

>>>SHORT LIGHTING
In this photograph, a single light source with an umbrella was used because of the same reason with former examples. The contrast between the highlights and the shadows created by this lighting are rather soft and smooth, and it made the person's face looks thinner. And, because I have used short lighting, there are some distracting reflections on the subject's eyeglasses.
In this case, the light source was placed like this:

>> ISO 800, 60mm, f/2.8, 1/500 sec.

>>>BROAD LIGHTING
This time, the broad lighting was used, and it made the model's face broader just like the previous example of a broad lighting.
And most importantly, by using this setting the distracting glare on the subject's eyeglasses were eliminated.
But what if I don't want any glares on the model's eyeglasses, but I don't want an effect of broad lighting either? --I think I've found my own solution for this dilemma, which is explained on the paragraph below.
In this case, the light source was placed like this:

>> ISO 800, 60mm, f/2.8, 1/640 sec.

>> ISO 800, 60mm, f/2.8, 1/400 sec.
>>>REACHING A COMPROMISE
In this photograph, the same light source as the other examples, but this time the light was moved a little bit to the left and placed a bit higher than the head height. By setting the light to this position, the light reflected from the eyeglasses went towards the ground and away from the lens, so the reflections were eliminated: Also, this is still a short lighting, since the left side of the model has been darkened and his face looks narrower.
However, I found that this is not a perfect solution for anyone with the eyeglasses.
This time, the model's eyeglasses had no frame on it (by chance), and thus it did not cast any shadows; but if the eyeglasses had a frame, it will cast shadows under the frame and it will be distracting. If that's the case, it would not be a good solution for the dilemma I mentioned in the example above.
In this case, the light source was placed like this:

>>Thoughts
In this experiment, I learned that the position of the main light strongly affects the appearance of the model's face, especially when the subject turned their head. The difference between the two different lighting--Broad and Short lighting-- was clear and I could understand the importance of an effective and deliberate use of light. Also, I found that it would be useful to enhance the characteristics of the subject's face by switching those two lighting.